Constructing the Copy of an Angle + Angles Activities

Explore the entire construction in the app above, then use the GeoGebra tools to draw segments and . Consider the triangles and . Show that the two triangles are congruent, that proves that angle is congruent to angle . (Use the Undo and Redo buttons at the top right of the toolbar, or refresh the browser page to delete possible objects you have created but that are not useful or correct).

When are two geometric objects said to be equal? And when they are said to be congruent? Which symbol indicates equality, and which one indicates congruency?

Draw on paper and define linear pair angles.

Draw on paper and define two vertical angles. What fundamental property do these angles possess?

If a statement is false, correct it to make it true, or provide a counterexample.

1. Two angles are supplementary if their sum is a straight angle.
2. The sum of the measures of two complementary angles is 180°.